With the advent and increasingly popularity of compact-disc read-only-memory (CD-ROM) technology and usage of the Internet, the viewing of digitally compressed video clips on personal computers (PC's) has also become very popular. For example, with respect to CD-ROM technology, a popular CD-ROM application is the encyclopedia, such as Microsoft's Encarta encyclopedia. A user is able to look up topics of interest, and for many such topics, can view a short video clip on a computer monitor. With respect to the Internet, many world-wide-web sites now include video clips, that can be instantly downloaded and viewed on a monitor.
Unlike other manners by which video may be viewed, such as film, television, video tape, and digital video disc (DVD), compression of source video into a relatively small file is important in CD-ROM and Internet applications (as well as in other applications). A CD-ROM typically only stores 650 megabytes of data, as compared to a DVD, for example, that may store four or five times this amount.
While streaming video applications on Internet web sites are generally not limited by storage capacity, they are limited by throughput: the typical consumer accesses the Internet via a 28.8K, 33.6K, or 56K baud modem. At this relatively slow data transfer rates (for example, the typical office environment local-area network (LAN) may offer transfer rates that are one hundred to one thousand times faster), the digitally compressed video clip must be able to be transferred quickly from the host web site to the consumer's computer, in order for the video to be optimally viewed.
Therefore, the computer industry has first turned to video compression algorithms in order to decode source video into relatively small digitally compressed video clips. For example, one common standard is the MPEG standard, developed by the Moving Picture Experts Group. The MPEG standard is available in different versions, such as MPEG-1, MPEG-2 and MPEG-4, where a higher number typically denotes a more robust and lenient compression algorithm. The MPEG standard is described in Roy Hoffman, Data Compression in Digital Systems, pages 113-119 (1997), which is hereby incorporated by referenced.
In the MPEG standard, as well as in other standards, a primary consideration is the "frame rate," or number of frames displayed per second, within the digitally compressed video clip. Generally, the higher the frame rate, the better the quality of the resulting video clip. Each frame within the clip may be an actual frame from the source video (digitally processed), or may be a blend of two or more frames from the source video. Furthermore, allowed in the MPEG-1, MPEG-2 and MPEG-4 standards, as well as in other standards, is the division of the video clip into two or more group of pictures (GOP's), or "shots," each shot including a number of frames of the clip. The division of the clip into shots permits each shot to have a different frame rate. This is desirable, because certain parts of the video clip may be displayed optimally with a lower frame rate than other parts (and thereby decreasing the overall size of the clip). This is true because parts of the video clip that show less motion than other parts generally do not need as high a frame rate.
While in theory the division of a video clip into a number of shots, each shot having a number of frames, is potentially desirable, it presents a difficulty in terms of efficient decoding of source video into such a video clip.
That is, dividing the video clip into shots, and further setting a different frame rate for each shot, is difficult to accomplish in conjunction with prior art technology. Specifically, except for the most highly experienced video processing professional, the decision as to the optimal frame rate to select for each shot within a video clip is a difficult one. There is a need, therefore, to ease such video processing. That is, there is a need to ease the division of a video clip, as decoded from a source video, into a number of shots, and further to ease the selection of a frame rate for each shot.